We have established a computerized data bank to store, retrieve and analyze an extensive collection (26 years/ greater than 200 patients) of epidemiological, clinical and laboratory information about the systemic vasculitides. We have continued to study the efficacy of daily low dose cyclophosphamide CP and prednisone as remission inducing and potentially curative therapy in systemic vasculitis. The long-term toxicity of daily CP therapy in some patients has led to studies of alternative treatment including (1) intermittent intravenous high dose CP, and (2) weekly low dose methotrexate (3) daily trimethoprim/sulfamethoxazole in limited Wegener granulomatosis (WG) and high dose intermittent intravenous immunoglobulin. We have evaluated various surgical interventions for the treatment of upper airway disease in WG. We have studied the sensitivity, specificity and prognostic value of the antineutrophil cytoplasmic antibody to determine its utility as a guide to therapy in WG. Because the vasculitides are rare disorders, clinical research has been limited by the inability of any single institution to recruit large numbers of patients. To address this issue we have organized an 8 site Multi-Center Collaborative Network that will address problems relating to epidemiology and treatment trials. The pathogenesis of the vasculitides has been investigated in vitro with the aid of endothelial cell systems to (1) characterize leukocyte binding to normal control and autologous endothelial cells, (2) determine whether sex hormones influence leukocyte-endothelial cell adhesion, a question that is particularly relevant to Takayasu arteritis, and (3) assess the role of haptoglobin in stimulating angiogenesis. An epidemiologic analysis of patients with WG has continued to evaluate environmental factors, such as inhalant exposure and patient clusters.